Not a GC/Wii Disc

I have softmodded my wii perfectly, have everything set, but for some reason 90% of the discs I burn I cannot play through the newest neogamma - usually as I run the disk, neogamma sais "Not a GC/Wii Disc". I have tried different ways of burning, different versions of downloaded iso, yet nothing still works.

Anyone know how I can fix this? I also changed the wii's region, console lang etc using ARC mod6 offline, yet still no difference. I am 100% sure the original iso works as it runs properly in dolphin and the DVD works because 2 of the burned games worked.

Can you try a USB drive and usb loaders with the same files? USB loading seems to be the preferred method these days, you may want to take that route in the end. At least you'll know if it's a bad file or bad burn.